The present invention generally relates to orthopedic traction devices. More specifically, it relates to a new orthosis which is used by an individual to apply a dynamically adjustable force in both flexion and extension to the joints of said individual's body for the purpose of stretching the soft tissues associated with these joints in order to restore lost or limited range of motion. The new orthosis provides an improved fit and function when compared with conventional orthoses.
Neurological impairment, physical trauma, surgery and prolonged immobility frequently lead to a loss of range of motion in a joint complex due to the contraction of associated “soft tissue.” As referred to herein, soft tissue includes: human ligaments, tendons, joint capsules, and other related structures. These soft tissues form a mesh-work of attached fibers which are connected at intervals throughout the tissue, and the longer the distance between the points of attachment, the greater the range of motion. The attachments can release or shift in response to prolonged tension, or additional attachments can develop at points of prolonged contact. The length of the fibers between the attachments can also increase or decrease depending on the presence or absence of force. When a joint is immobilized for a period of time, such as when a patient's limb is immobilized in a cast or splint in order to allow a broken bone to heal, connected tissue at the joint tends to shorten, resulting in a decreased range of motion at the joint. This condition is exacerbated by the length of time the joint is immobilized. Moreover, when surgery involves the cutting open of a joint capsule, the scar tissue that forms when this tissue heals is inherently less supple and less conducive to motion. If not treated appropriately, this post-surgical scar formation can severely limit a patient's normal range of motion.
According to Davis's Law, soft tissue remodels itself based upon the forces applied to it. Therefore, although scarring is inevitable, the nature and structure of the scar tissue itself is malleable. In fact, collagen, which comprises scar tissue, can be lengthened when the appropriate forces are imparted upon it. Rehabilitation efforts to reduce or stretch such contractions usually involve extensive physical therapy or surgical intervention. Both physical therapy and surgical alternatives frequently include the use of some form of orthopedic device such as a splint. Although some splints may have attributes of both, orthopedic splints generally fall into one of two general categories known as static or dynamic. Static splints are primarily designed to hold the affected limb or digits at a preset position and may be manually adjusted to accommodate different desired settings. Serial casting is a form of static splinting where a series of castings hold the limb or digits in a succession of positions. Static splints are commonly used to: restore range of motion, prevent the occurrence of soft tissue contraction associated with long term immobilization, hold limbs in the desired post-surgical position during healing, and aid as a mechanical support for ambulation. Dynamic splints have a similar purpose to static splints but use components such as springs or elastic bands in order to provide an active tension as the soft tissues stretch, in essence taking up the slack. As with static splints, dynamic splints are designed to improve range of motion by exploiting the viscoelastic properties of soft tissue. The dynamic splints are worn over a period of time, such as when a patient is sleeping, in order to stretch the connected tissue by providing a prolonged, constant, low intensity stretching in order to develop the patient's full range of motion.
Various dynamic splint mechanisms are described in U.S. Pat. Nos. 4,397,308, 4,485,808, 4,508,111, 1,538,600 and 4,657,000 to George R. Hepburn, all of which are incorporated by these references. The basic design is an adjustable splint assembly comprising a lower strut and an upper strut pivotally connected to said lower strut, one of said struts having at one end a pivotally mounted head portion defining a cam surface, an adjustable biasing means mounted within the other strut and biased into engagement with said cam surface, for applying a quantifiable force tending to align or approximate said upper and lower struts and means for securing said splint assembly to a limb.
Another similar device, Malewicz et. al. U.S. Pat. No. 5,437,619, which is incorporated by this reference, utilizes coil springs as the connection between two sections of a brace to provide a resistance force to motion. However, it can be difficult for the patient to access or adjust the spring tension device while the device is being worn, especially for arm braces.
In another known device, Bonutti U.S. Pat. No. 5,167,612, which is incorporated by this reference, two cuffs are provided for attachment to a patient's limb with a tensioning tower attached between the two cuffs to provide a mechanical advantage for increasing range of motion of the joint. The tower is a box-like structure which includes a drive mechanism for loading and unloading the cuffs to apply force to the limb. The tower device is fairly large and awkward, however, and may not be suited for long term wear by a patient, such as when a patient is sleeping.
Other conventional devices include a rigid element (including a turn buckle) on the inside angle of a joint between two cuffs attached on either side of a joint of a patient's limb and use the turn buckle to vary the length to push or pull the limb segments relative to each other. With this rigid system, the joint is essentially locked at a predetermined position. There is no give or elasticity and as a result, the joint and its tissues fill with lactic acid and cellular waste which pools and leads to discomfort.
Another known device utilizes an airbladder from a blood-pressure cuff to push down one side of a joint while a large cumbersome metal frame and pivotable rod holds the other side of the joint in a fixed relative position. Obvious faults with this device are its extreme bulk and cost of manufacture. Other drawbacks include the inability to stretch a joint in both directions as well as the limited scope of affecting only one joint in the body, the great toe. Yet another drawback of this device is the fact that all joints of the foot are affected during treatment, so that if other digits have been operated on (as is often the case) they will be affected whether or not this is warranted or desired.
Although many of these known adjustable splints operate similarly to each other in applying tension across a joint, they are relatively heavy and bulky and consequently impede, to some extent, free activity at the affected joint. The heavy, tubular strut assemblies used in conventional splints are generally not coextensive from the connecting pivot point, and thus may only be brought into a parallel aligned relationship rather than axially aligned. It is impossible to contour these heavy struts to conform to the limb of a user, and the degree of pivotal movement permitted by such splints is generally much less than 180 degrees. Moreover, misapplied force from a poorly designed or poorly fitting splint can force the limb or digit outside the natural range of motion and destabilize the joint or cause permanent damage to the soft tissues. The distortion of padding and strap attachments, when placed under tension, can result in twisting of the splint's attachments at their intersections with the rigid structural components. This twisting distortion allows the structural components to shift from their desired alignment position, resulting in unintended joint stresses, and uneven distribution of pressure and constriction of soft tissue.
Finally, with known adjustable splints, the bias force adjustment mechanism is often difficult to reach, and the degree of adjustment is often difficult to see. The user must use reading glasses and squint to see the differing levels of force applied. Accurate adjustment of the bias for such splints when they are in place is not easily accomplished either, often requiring fine motor skills to operate small screwdrivers to engage smaller screws that are located inside the device and out of sight. Many patients must have someone do this for them due to the amount of effort required to fit and adjust these splints. Because such splints are generally required to be worn several times per day, it becomes obvious that this is a great difficulty even if the wearer has the luxury of having someone present to assist. Another drawback that stems from the difficulty of putting on and taking off these splints from a lower limb or digit arises when a patient needs to ambulate. This would come in to play if the patient required using the restroom, answering the phone, or getting a drink from the kitchen. In most conventional splints this process would be time consuming and difficult to the point that the patient would consider it too much of a burden to utilize the device.
It would be desirable to provide a device which can be worn by a patient for a long period of time, such as overnight while the patient sleeps, which provides an adjustable, controlled amount of force to the limb to allow for a gradual stretching action. It would also be desirable to use a force adjusting mechanism that has the ability to quickly release undesired or painful force with an easy pull of a tab. Additionally, it would be advantageous to provide a device in which the location of the force applying mechanism can be adjusted to a position where it is easily accessible for adjustment by the patient or in a position where it will cause the least patient discomfort. Yet another advantage would be to have the ability to go from using the device on a right-sided limb or digit to a left with little or no difficulty. Also desirable would be to have a dynamic splint that is lightweight and user friendly, one that can be easily taken to work in a handbag or briefcase and put on and taken off with great ease. And finally, a great advantage of a splint in this field would be to have the versatility to be used for both flexion and extension of a limb or digit as well as to have the adaptability to affect single or multiple digits if required without having to be extensively reconfigured.